Nitride semiconductor substrate and method for manufacturing same

Abstract

A nitride semiconductor substrate including a growth substrate, and a nitride semiconductor thin film formed on the growth substrate, in which the nitride semiconductor thin film includes an AlN layer formed on the growth substrate and a nitride semiconductor layer formed on the AlN layer, and an average concentration of Y (Yttrium) in the AlN layer is 1E15 atoms/cm3 or higher and 5E19 atoms/cm3 or lower. Thereby, a nitride semiconductor substrate is capable of improving the surface morphology of an AlN layer, thereby suppressing the generation of pits on the surface of a nitride semiconductor epitaxial wafer, and a method manufactures the nitride semiconductor substrate.

1 .- 21 . (canceled) 
     
     
         22 . A nitride semiconductor substrate comprising:
 a growth substrate; and   a nitride semiconductor thin film formed on the growth substrate, wherein   the nitride semiconductor thin film includes an AlN layer formed on the growth substrate and a nitride semiconductor layer formed on the AlN layer, and   an average concentration of Y (Yttrium) in the AlN layer is 1E15 atoms/cm 3  or higher and 5E19 atoms/cm 3  or lower.   
     
     
         23 . The nitride semiconductor substrate according to  claim 22 , wherein
 a thickness of the AlN layer is 50 to 150 nm, and   an average concentration of Y (Yttrium) from directly above the growth substrate to 300 nm in a thin film growth direction in the nitride semiconductor thin film is 1E15 atoms/cm 3  or higher and 5E19 atoms/cm 3  or lower.   
     
     
         24 . The nitride semiconductor substrate according to  claim 22 , wherein
 the nitride semiconductor layer comprises one or more of GaN, AlN, and AlGaN.   
     
     
         25 . The nitride semiconductor substrate according to  claim 22 , wherein
 the growth substrate is a substrate having a single-crystal silicon layer formed on a composite substrate with a plurality of layers laminated together, and   the nitride semiconductor thin film is formed on the single-crystal silicon layer.   
     
     
         26 . The nitride semiconductor substrate according to  claim 25 , wherein
 the single-crystal silicon layer has a thickness of 100 to 500 nm.   
     
     
         27 . The nitride semiconductor substrate according to  claim 25 , wherein
 the composite substrate includes a polycrystalline ceramic core, a first adhesive layer laminated entirely to the polycrystalline ceramic core, a second adhesive layer laminated entirely to the first adhesive layer, and a barrier layer laminated entirely to the second adhesive layer, and   the single-crystal silicon layer is formed on a planarization layer laminated to only one surface of the composite substrate.   
     
     
         28 . The nitride semiconductor substrate according to  claim 27 , wherein
 the composite substrate includes a conductive layer laminated entirely to the first adhesive layer, between the first adhesive layer and the second adhesive layer.   
     
     
         29 . The nitride semiconductor substrate according to  claim 25 , wherein
 the composite substrate includes a polycrystalline ceramic core, a first adhesive layer laminated entirely to the polycrystalline ceramic core, a barrier layer laminated entirely to the first adhesive layer, a second adhesive layer laminated to a back surface of the barrier layer, and a conductive layer laminated to a back surface of the second adhesive layer, and   the single-crystal silicon layer is formed on a planarization layer laminated on a front surface of the barrier layer of the composite substrate.   
     
     
         30 . The nitride semiconductor substrate according to  claim 25 , wherein
 the composite substrate includes a polycrystalline ceramic core, a first adhesive layer laminated entirely to the polycrystalline ceramic core, a conductive layer laminated to a back surface of the first adhesive layer, a second adhesive layer laminated to a back surface of the conductive layer, a barrier layer laminated to a front surface and a side surface of the first adhesive layer, a side surface of the conductive layer, and a side surface and a back surface of the second adhesive layer, and   the single-crystal silicon layer is formed on a planarization layer laminated on a front surface of the barrier layer of the composite substrate.   
     
     
         31 . The nitride semiconductor substrate according to  claim 28 , wherein
 the conductive layer includes a polysilicon layer.   
     
     
         32 . The nitride semiconductor substrate according to  claim 28 , wherein
 the conductive layer has a thickness of 150 to 500 nm.   
     
     
         33 . The nitride semiconductor substrate according to  claim 27 , wherein
 the polycrystalline ceramic core contains aluminum nitride.   
     
     
         34 . The nitride semiconductor substrate according to  claim 27 , wherein
 the first adhesive layer and the second adhesive layer include a tetraethyl orthosilicate (TEOS) layer or a silicon oxide (SiO 2 ) layer, and   the barrier layer contains silicon nitride.   
     
     
         35 . The nitride semiconductor substrate according to  claim 27 , wherein
 the first adhesive layer and the second adhesive layer have a thickness of 50 to 200 nm, and the barrier layer has a thickness of 100 to 350 nm.   
     
     
         36 . The nitride semiconductor substrate according to  claim 27 , wherein
 the planarization layer contains tetraethyl orthosilicate (TEOS) or silicon oxide (SiO 2 ) and has a thickness of 500 to 3000 nm.   
     
     
         37 . A method for manufacturing a nitride semiconductor substrate having a growth substrate and a nitride semiconductor thin film formed on the growth substrate, the method comprising the steps of:
 (1) providing the growth substrate containing Y (Yttrium); and   (2) epitaxially growing an AlN layer on the growth substrate and then epitaxially growing a nitride semiconductor layer on the AlN layer, thereby forming the nitride semiconductor thin film, wherein   in the step (2), Y in the growth substrate is diffused so that an average concentration of Y (Yttrium) in the AlN layer is 1E15 atoms/cm 3  or higher and 5E19 atoms/cm 3  or lower.   
     
     
         38 . The method for manufacturing a nitride semiconductor substrate according to  claim 37 , wherein
 the AlN layer has a thickness of 50 to 150 nm, and   an average concentration of Y (Yttrium) from directly above the growth substrate to 300 nm in a thin film growth direction in the nitride semiconductor thin film is 1E15 atoms/cm 3  or higher and 5E19 atoms/cm 3  or lower.   
     
     
         39 . The method for manufacturing a nitride semiconductor substrate according to  claim 37 , wherein
 the growth substrate is configured with a composite substrate including a polycrystalline ceramic core containing Yttria (Y 2 O 3 ) as a bonding material, a first adhesive layer laminated entirely to the polycrystalline ceramic core, a second adhesive layer laminated entirely to the first adhesive layer, and a barrier layer laminated entirely to the second adhesive layer; a planarization layer laminated to only one surface of the composite substrate; and a single-crystal silicon layer formed on the planarization layer; and the nitride semiconductor thin film is formed on the single-crystal silicon layer, and   the average concentration of Y (Yttrium) in the AlN layer is 1E15 atoms/cm 3  or higher and 5E19 atoms/cm 3  or lower by adjusting a thickness of the barrier layer in advance.   
     
     
         40 . The method for manufacturing a nitride semiconductor substrate according to  claim 39 , wherein
 the composite substrate includes a conductive layer laminated entirely to the first adhesive layer, between the first adhesive layer and the second adhesive layer.   
     
     
         41 . The method for manufacturing a nitride semiconductor substrate according to  claim 37 , wherein
 the growth substrate is configured with a composite substrate including a polycrystalline ceramic core containing Yttria (Y 2 O 3 ) as a bonding material, a first adhesive layer laminated entirely to the polycrystalline ceramic core, a barrier layer laminated entirely to the first adhesive layer, a second adhesive layer laminated to a back surface of the barrier layer, and a conductive layer laminated to a back surface of the second adhesive layer; a planarization layer laminated to a front surface of the barrier layer of the composite substrate; and a single-crystal silicon layer formed on the planarization layer; and the nitride semiconductor thin film is formed on the single-crystal silicon layer, and   the average concentration of Y (Yttrium) in the AlN layer is 1E15 atoms/cm 3  or higher and 5E19 atoms/cm 3  or lower by adjusting a thickness of the barrier layer in advance.   
     
     
         42 . The method for manufacturing a nitride semiconductor substrate according to  claim 37 , wherein
 the growth substrate is configured with a composite substrate including a polycrystalline ceramic core containing Yttria (Y 2 O 3 ) as a bonding material, a first adhesive layer laminated entirely to the polycrystalline ceramic core, a conductive layer laminated to a back surface of the first adhesive layer, a second adhesive layer laminated to a back surface of the conductive layer, and a barrier layer laminated to a front surface and a side surface of the first adhesive layer, a side surface of the conductive layer, and a side surface and a back surface of the second adhesive layer; a planarization layer laminated to a front surface of the barrier layer of the composite substrate; and a single-crystal silicon layer formed on the planarization layer; and the nitride semiconductor thin film is formed on the single-crystal silicon layer, and   the average concentration of Y (Yttrium) in the AlN layer is 1E15 atoms/cm 3  or higher and 5E19 atoms/cm 3  or lower by adjusting a thickness of the barrier layer in advance.